Dynamometer and power absorption device



ec. 18, 1%2 A, J. wARsAw DYNMOMETER AND POWER BSORPTION DEVICE 4Sheets-Sheet l Filed Nov. 12, 1958 ec. 18, E962 A. J. WARS/awDYNAMOMETER AND POWER ABSORPTION DEVICE 4 Sheets-Sheet 2 Filed Nov. l2,1958 ww .15% i@ llllll l IV. il .HHMHHHIIHNQIHI n I INVENTOR, ARTI-luaJ. WAnsAw Dec. 18, i962 A. J. wARsAw DYNMOMETER AND POWER ABSORPTIONDEVICE 4 Sheets-Sheet 3 Filed Nov. 12, 1958 INVENTOR. Amma WARSAW Dec.18, 1962 A. .n.rwARsAw DYNAMOMETER AND POWER ABSORFTION DEVICE 4Sheets-Sheet 4 Filed Nov. l2, 1958 INVENTOR. Awa-Hu@ Jwmsml Y assessPatented ec. 18, 1962 3,068,639 DYNAWWTER AND PGWER ABSSRPTION DEVlCEArthur J. Warsaw, Colfax, El. Filed Nov. 12, 1958, Ser. No. 773,268 l@Claims. (Cl. 73-135) This invention relates to improvements in adynamometer and power absorption device and refers particularly to adevice of the character described wherein a prime mover may beaccurately and constantly loaded and wherein the power may be dissipatedrapidly and at a substantially constant rate and in an eflcient manner.

The present invention relates to that type of dynamometer wherein theenergy of a prime mover may be converted into heat by friction means,the friction applying means being such and the heat -dissipation meansbeing such, that a substantially constant controlled load may be appliedto the prime mover and the frictionapplying means, the brake linings,will not be excessively worn or rapidly disintegrated.

Briefly described, the device comprising the present invention comprisesa stationary casing which is lled with, and through which a coolingliquid is circulated. A hollow liquid-tight drum is positioned in thecasing and is immersed in the cooling liquid. Means is contemplated forrotating the drum within the casing, the drum being operativelyconnected to a prime mover under test. Braking means is positionedwithin the drum for loading the prime mover, the braking force beingremotely controlled, and where the device is to be used as adynamometer, measuring means is associated with the braking means tomeasure the torque exerted by the drum on the braking means. Where thedevice is used merely as a power absorption unit, no measuring means isemployed with the braking means.

One of the important features of the invention resides in the fact thatthe drum, carrying the braking means, thaL is, the seat of energyconversion, is completely immersed in a circulating cooling liquid andthe energyconverting surfaces are efficiently and uniformly cooled.

Another feature of the invention resides in a braking force applyingmechanism which is remotely controlled, preferably being located at acontrol station wherein all factors pertaining to the test, such as,torque readings, rpm. readings, etc. are under the ready observation ofthe operator.

A further feature of the invention resides in the unique manner in whichthe brake linings are mounted in the braking mechanism whereby saidlinings may be removed or changed with the expenditure of a minimum oftime and labor.

An additional feature of the invention resides in a unique forceapplying mechanism wherein a balanced force is applied symmetrically tothe braking surfaces.

Further features, objects and advantages of the present invention willbe apparent from the accompanying drawings and following detaileddescription.

in the drawings,

FEC'. 1 is a longitudinal sectional View taken through the dynarnometerembodying the features of the present invention.

HG. 2 is a transverse sectional view taken on line 2-2 of FiG. l.

lG. 3 is a transverse sectional View taken on line 3-3 of FIG. l.

PEG. 4 is an end elevational view of the dynamometer.

`EG. 5 is a detailed sectional view of a modified reaction cylinder.

Referring in detail to the drawing, the dynamometer embodying thepresent invention comprises essentially a power absorption unit l and atorque measuring mechanism 2. The power absorption unit comprises acasing having a base 3, end walls 4i and 5, opposite side walls 6 and anopen top. The casing is adapted to be liquidtight and, as will behereinafter more fully described, means is provided for circulating acooling liquid through the casing. A closure 7 is contemplated for theopen top of the casing, the closure carrying downwardly extendingflanges 8 around its periphery. A gasket 9 is carried by the closure,said gasket being slotted to receive the upper defining edges of theside and end walls. The gasket may be constructed of resilient rubber orother suitable gasket material.

A vhook l@ is secured to each of the end Walls 4 and 5, preferably bywelding 11, and similar hooks 12 are similarly secured to the side walls6, the hooks 10 and l2 being disposed adjacent the corners of the casingwhich is preferably rectangular in horizontal section. Eyebolts 13 areadatped to engage with the hooks 1i) and 12, the upper ends of theeyebolts carrying screw threads la. The upper ends of the eyeboltsextend through suitable apertures in the closure 7 and nuts 15 engagethe threaded ends of the eyebolts to securely seat the closure 7 uponthe open end of the casing, the gasket 9 rendering the closure liquidtight.

End wall 5 of the casing is provided with an opening le in which abushing 17 is carried, said bushing being secured by bolts 18 to thewall. A shaft 19 extends through the bushing 17 from the exterior of thecasing to the interior thereof and a seal 26, carried by the bushing,embraces the shaft 19 within the casing to prevent liquid from withinthe casing leaking along the surface of the shaft exteriorly of thecasing. A bearing housing 2l is secured by bolts 22 to the bushing 17and said bearing housing carries a ball bearing assembly 23. The ballbearing assembly comprises an outer race 24 which is carried by thebearing housing and an inner race 25 which comprises essentially ahardened sleeve which embraces the shaft 19 exteriorly of the housing. Acollar 26 is rigidly secured to the shaft 19 by means of set screw 27,said collar holding the sleeve 25 in position. A conventional coupling28 is secured to the end of the shaft i9 by means of set screw 29, saidcoupling being adapted to engage with a companion coupling carried bythe prime mover (not shown) under test. Of course, any suitable type ofcoupling is contemplated.

Within `annular space 30 provided by the bushing 17 and bearing housing21 a grooved pulley 31 is positioned, said pulley being rigidly securedto shaft 19. A block 31 is also secured to the outer surface of wall 5and said block carries a `shaft 32 journaled in ball bearings 33. Ashaft 32 carries a grooved pulley 34 and an endless belt 35 operativelyconnects pulley 3l and pulley 34 to rotate shaft 32 in timedrelationship with the rotation of shaft 19. The shaft 32 carried by theblock 3l is connected to a iexible cable 36 which is housed within asuitable` sheath 37, the cable at its `opposite end being connected to aconventional tachometer 38 whereby the speed of shaft 19 may bemeasured.

Within the casing, shaft 19 carries `a flanged coupling 39 which isrigidly secured to the shaft. The coupling 39 carries screws it? whichengage in an end wall 4l or" a drum- 42, a gasket 43 being positionedbetween the flanged coupling 39 and the wall 41.

The drum 42 is cylindrical and the side wall 44 thereof carries aplurality of ribs or fins 45. The drum 42 is open at the end thereofopposite the end wall 4l and a closure 46 functions, as will behereinafter more fully described, to completely close the drum.

End wall 4- of the outer casing carries a hose coupling 47 controlled bya valve d, the hose coupling 47 being adapted to be connected with asuitable source of cooling liquid. A pipe 49 (FIG. 3) entends throughthe base 3 of epesses au outer housing and extends upwardly into theinterior of `the housing, said pipe opening adjacent the central portionof the housing. The pipe 49 is adapte to be connected to a suitableconduit whereby cooling liquid under a desired pressure may vbeintroduced through the coupling i7 into the casing and dischargedthrough pipe e9. ln the normal operation of the device the interior ofthe casing is adapted to be completely filled with cooling liquid asindicated at Sil in FIG. 3, said liquid entering through the coupling 47and discharging through the outlet i9 at a rate so controlled as to keepthe interior of the casing substmtially lled. In view of the fact thatthe interior ofthe casing is adapted'to be completely iiiled withliquid, it can readily be seen that the drum 42 will be completelyimmersed in the liquid. Hence, precautions are taken to render theinterior of the drum liquid-tight.

rhe lend wall 4 of the liquid casing is provided with a central aperture51 and a bushing 52 is positioned in said aperture, said bushing beingsecured Vto wall 4 by means of bolts 53 or the like. The bushing 52carries a `self-aligning bearing 54 which in turn functions as a bearingfor a shaft S which extends through the bushing into the'interior lofthe liquid casing. The end wall 41 of drum 42 Vis provided with acentral aperture 56 and the inner end of shaft 55 extends into saidaperture. A ball bearing yassembly 57 is positioned between the definingWalls 'of the aperture 56 and the end of shaft S5. The

closure 46 for the drum, opposite end wall 4i thereof, i-ssecured'to theopen end of the drum by means of screws '58. The central portion of theclosure 46 is provided with a central opening 59 between which and shaftSS a ball bearing assembly 60 is positioned. Thus, when shaft I9 isrotated 'by the prime mover, the Idrum 42 will be Yrotated and willrotate independently of lshaft 55, the freedom of relative rotationbeing accomplished by -the ball bearing assemblies 57 and 69. A sleeve6i is rim'dly secured in theopening '59, said sleeve circumscribingshaft 55 and extending outwardly from the drum. Packing rings 62 and 63are carried by the sleeve 61 `and prevent liquid'from the interior ofthe casing from moving along shaft 55 Vinto the drum through opening 59.A packing ring 764 circumscribes the sleeve 6i and is confined betweensaidY sleeve and flange 65 of bushing 52. Thus, liquid which may seeppast packing ring 64.- will enter the space 66 and'move into the space67 and there will be little or no tendencyfor such liquid to move alongshaft 55 beneath the packing rings V62 and 63.

A holder 68 is positioned upon the torque shaft 55 and is rigidlysecured thereto by :a suitable key (not shown) or other suitablesecuring means. The holder 63 comprises a cylinder block 69 whichterminates `adjacent shaft 55 ina hub portion 79. Rings 7l embrace shaft55 and one such ring is disposed adjacent and secured to each end ofvhub portion 7% by means of screws 72. Each of the rings 71 is providedwith an :annular recess which carries a packing ring '73@V Y Thecylinder portion 69 of the holder 6d comprises an are disposed in thegrooves S2 of diametrically opposite brake shoes Sl. ne respective endof cach spring 33 carries a hook S4 and the opposite end of each springcarries an eye 85, whereby, when each spring is operatively mounted, anendless 'spring circumscribes and exerts a resilient force upon therespective end portions of each diametrically opposite shoe Si. Thus,four virtually endless coil springs 33 function resiliently to hold thefour shoes Si in properly seated position upon the balls 79' of eachpiston 77.

The holder 63 also carries four radial projections S6 which areangularly spaced 90 from each other and are angularly spaced fromrespective adjacent cylinders 7d. The projections Se are arcuate attheir radial exf tremities and terminate short of, but closely adjacent,the inner surface of the cylindrical wall of the drum 42.

Between each pair of projections de an arcuate friction element 87 ispositioned, each friction element being disposed between the outersurface of each shoe Si andthe inner surface of the cylindrical wall ofthe drum d2. As will be hereinafter morerfully described, the frictionelements are loosely positioned in the spaces defined by adjacentprojections 86, a shoe Si, a portion of the interior wall of the drum42, and the end walls il and 46 of the drum. This arrangement greatlyfacilitates the insertion and removal of the friction elements since itis merely necessary, after the closure 4e has been removed from thedrum, to axially slide the friction elements into or out of operativeposition.

ln the operation of the device, fluid under pressure isY introduced intoeach cylinder 74 from the bores 75 and 76, as will be hereinafter morefully described, to urge simultaneously the pistons 77 radiallyoutwardly. The shoes 81 are thus simultaneously urged radially outwardlyinto contact with the friction elements S7 which latter are therebyurged into frictional contact with the interior wall of the drum.

It will be noted that the radial force exerted by each piston acts alongthe axis of the cylinder and piston and,

hence, there is a tendency for the force to be more orY lessconcentrated at the central 'portion of each friction element. To moreuniformly distribute the force dev livered by the pistons over theentire arcuate outer surface of the friction elements, each shoe '71 isprovided with a central flattened portion 8S which is spaced fromcontact with the interior surface of each friction element. Thus, theconcentration of force at the central portion of each friction elementis more uniformly distributed over theV of riuid necessary to move thepistons -is Vrelatively small,

4 pump 9d may conveniently bea hand pump manipulated annular castingwhich, in preferred form, carries four Y, cylinders 74 which areangularly spaced 90 from each cal ball 79, which, in turn, loosely seatsina companion socket 8% provided in a force-producing brake shoe Si.Each brake shoe 8l is provided with a pair of spaced Vtransverse,grooves S2. To hold the brake shoes gli in seated position upon theYballs 79 a pair Vof coil springs S3 The cylinders 74 open Y Vby lever9i. The pump 94B may also be provided With a pressure release 92 torelieve the pressure in the cylinders when it is desired to retract theshoes 3l. When the pressure is released, springs S3 retract the pistons77 and shoes 81. Y

The 'device thus far described is essentially aY power ab-V sorptionunit and operates as follows: TheY outer iiuid casing is first closed bypositioning the closure 7 upon the kupper end thereof and manipulatingVthe nuts l5 to render the closure liquid-tight. The coupling 25 may beconnected to the prime mover, the mechanical power ofv which is therebyabsorbed or converted. A cooling liquid Vunder pressure is circulatedthrough the outer casing at a desired rate so controlled as to keep theinterior of the casing substantially completely filled with liquid. Thecirculation of the liquid is such that as the liquid acquires heat fromthe operation of the device it is removed but the removal is socontrolled as to not deplete the body of A fluid pump Y iiquid in thecasing. A suitable pump (not shown) may function to circulate thecooling liquid and if the cooling liquid is to be maintained in a closedcircuit, a suitable radiator or heat exchanger will be incorporated inthe piping circuit exteriorly of the casing.

When the prime mover is actuated the drum 42 rotates therewith. Gfcourse, the rotation of the drum, in itself, furnishes only a small loadupon the prime mover. To augment 'the load, the pump 90 may be actuatedto supply duid under pressure to the cylinders 74. The pistons arethereby urged radialiy outwardly, in turn, moving the shoes 81 outwardlyinto pressure contact with the inner surfaces of the arcuate frictionelements 87. The outer surfaces of the friction elements 87 are thusbrought into frictional contact with the inner surface of thecylindrical lwall of the drum 42. Initially the friction elements S7tend to move circularly with the drum, this initial movement beingaccommodated by the clearance spaces between the ends of the frictionelements and the projections 86. Thereafter the frictional contact ofthe friction elements and the interior of the drum functions to exert atorque upon the holder 68 which, in turn, is transmitted to the torqueshaft S5. If the device is to be used merely as a power absorption unit,the torque shaft 55 may be locked exteriorly of the casing by anysuitable means.

In this fashion a controlled load may be applied to the prime mover. Themechanical movement of the prime mover is thereby converted into heatwhich is generated at the contacting surfaces of the friction elements87 and the drum d2. In view of the fact that the entire drum is immersedin a body of cooling liquid and that this liquid is circulated throughthe drum, provides means for removinff the heat generated at thefriction surfaces. To facilitate the heat transfer from the frictionalcontacting surfaces, the outer cylindrical wall of the drum is providedwith iins or ribs 45 which increases the area of contact of the coolingmedium and the drum wall. In addition, the ribs 4S function to preventdistortion of the cylindrical wall of the drum when said wall issubjected to the frictional heat and is also subjected to the radialpressures exerted by the friction elements S7.

it is of importance, whether the device comprising the present inventionis employed as a power absorption device or as a dynamometer, that theload applied to the prime mover be as constant as possible. Hence, bypreventing distortion of the cylindrical wall of the drum 42, thefriction elements will make uniform contact with the interior surface ofthe wall. In addition, by virtue of the flattened portions 8S of theshoes $1, the radial forces applied by the pistons 77 will be moreuniformly distributed over the contact area of the friction elements S7and the drum and no local hot spots will develop in the frictionalcontact areas. If such hot spots were to develop, the friction materialswould not only be unduly worn but their coeliicient of friction would benonuniform.

it will be noted that the force-applying agents, that is, the pistons77, are symmetrically disposed relative to the axis of the torque shaftS5. Four such actuating pistons are shown and constitute the preferredarrangement. However, more cylinder and piston pairs may be employed,for instance, six piston-cylinder arrangements may be employed. If,however, in the use of the device it is not necessary to apply a uniformload to the prime mover, three or more piston-cylinder pairs may beemployed with the appropriate number of shoes and friction elements.

The friction elements S7 may comprise any suitable friction materialsuch as the conventional resin bonded asbestos friction material or, ifdesired, the elements may comprise conventional powdered metal frictionmaterials or may even comprise solid metal friction elements.

When the device embodying the concepts is to be used as a dynamometer,instead of blocking the torque shaft 55, an arm 93 of predeterminedlength carries a sleeve 94 which is keyed by key 95 to the end portionof the torque shaft exteriorly of the cooling liquid casing. A reactioncylinder housing 96 is pivotally mounted upon the wall 4 of the coolingliquid casing. Although, the device shown in FIG. 5 is a slightmodification of the invention, the casing 96 and casing 96 of themodification are pivotally mounted in the same fashion. Hence, thepi-votal mounting of casing 96 will be described in detail, it beingunderstood that the casing 96 is mounted in the identical manner.

A portion of casing 96 carries a ange 97 and casing 96 carries anidentical ange 97. An aperture 98 is provided in ange 97 and anidentical aperture is provided in flange 97. A bearing 99 is secured towall 4 and extends loosely through aperture 98. A locking ring 100prevents removal of the flange 97 from its position on the bearing 99.An arcuate groove 101 is provided in the wall of the casing 96', saidarcuate groove having a radius of curvature equal to the distance fromthe axis of bearing 99 and the axial center of the groove 101. Ballbearings, one of which is shown at 102 in FIG. 5, are carried in thegroove 101 whereby swingable movement of the casing 96 upon bearing 99'is facilitated. The identical structure is also contemplated in casing96.

A hardened steel spherical abutment 103 is carried by arm 93 adjacentits free end, the abutment bearing upon the head of a piston 104slidably positioned in cylinder 105 provided in casing 96. A coupling106 connects into the lower portion of cylinder 105 and a conduit 107connects the coupling to a conventional uid pressure gauge 108. vWhenthe pistons 77 are retracted, that is, when no torque is applied toshaft 55, the cylinder 105 beneath piston 104 together with the conduit107 and al1 connecting liquid space, is filled with liquid. Thearrangement is such when pistons 77 are actuated to load the primemover, as hereinbefore described, a torque is applied to shaft 55tending to rock arm 93 and depress piston 104. Pressure is therebyestablished in' the liquid in cylinder 105 and said pressure isindicated upon the meter 108. Relating the radius arm of drum 42 to theradius arm `of arm 93 and the area of piston 104, the meter 108 may becalibrated in terms of torque.

In practice, the pump 90 and meter 108 may be positioned at a controlstation which may, if desired, be positioned remote from thedynamorneter. Thus, the actuation of the device and the resultant torqueindications are convenient to the operator. To secure a powermeasurement the tachometer 38 may also be positioned at the controlstation and, if desired, the calibrations of meter 108 may be related tor.p.m. of the drum to give a directindication of power.

Referring particularly to FiG. S, parts of which have already beendescribed, the casing 96 is provided with cylinder 105 in which a piston104 may be slidably positioned. With the exception of piston 104', thereaction unit 2 is the same as has been hereinbefore described.

The piston 104 is a compound assembly, the piston comprising a sleeve109 which is slidably positioned in cylinder 105 within which a secondpiston 110 is slidably carried. It can readily be seen that the piston104' as a While is of a predetermined area and the piston 110 is of asmaller predetermined area. Hence, the liquid beneath the piston 104 andthe liquid spaces connected there to can be pressurized by either ofsaid pistons. 'Ihus for a predeterminted torque output of shaft 55different readings will appear on meter 108 which are related to eachother in proportion to the relationship of the area -of piston 104' as awhole' and the area of piston 110 alone.

'Ihe sleeve 109 of piston 104' carries a locking ring 111 which engagesin the cylinder wall. In addition, piston 110 carries a locking ring 112which, when the arm 93 'moves to pressurize the liquid in cylinder 105',abuts against the top of sleeve 109. 'Ihe arrangement is such, that byremoving ring lll operative movement ot' arm 93 will cause piston 194 todescend as a unit, utilizing the full area of piston 101i to pressurizethe reaction liquid, Whereas if ring 112 is removed only piston 110 willbe actuated to pressurize the reaction liquid. lr ring 112 is removed,of course, it is immaterial whether ring 1311 is in place or not sincethe force transmitted by arm 93 will only be applied to piston 11G.

Thus, the ranges of torque or power measured by meter 108 may be variedand meter 108 may be calibrated accordingly.

In applying the torque of shaft 55 to pistons 104 or 164', considerablepressure is established between ball "163 and the top ofthe piston. Ashas been hereinbefore described, ball 103 is preferably constructed ofhardened steel to better withstand this pressure. Likewise the heads ofpistons 104 or 104' may be constructed of hardened steel or hardenedsteel inserts (not shown) may be carried by Said piston heads. a l

Further, ball 103 is carried by arm 93 and, hence, when said arm moves,ball 103 moves in an arc. Hence, the tangent position occupied 4by theball is along an arc and .if the casings 96 and 06' were stationary, asliding con- Vtact would occur between the ball 103 and the heads ofpistons d or 104'. Considerable wear would thus take place at thecontacting7 surfaces and the force of ball 103 would not always betransmitted along the axis or the piston. However, by the provision ofbearing 99', or its equivalent relative to casing 96, the casings 96 or96 are swingable and thus, when the force of ball 103 is brought to bearon the piston head the casing will swing until said .forceacts along theaxis of the piston 104 or 104. This expedient prolongs the life of thecontacting surfaces, the

.ball and piston heads. In addition, a more eiiicient transmission offorce occurs between the ball and piston head and the piston Will alsobe relieved of a lateral thrust which would otherwise occur.

As has been hereinbefore described, the present device may be used as apower absorption or conversion unit or a dynamometer and in either useits manifest advantages .are numerous. Modifications `of use andenvironment are contemplated and unpatentable structurel modifications.Will occur to one skilled in the art. Hence, it is not yintended thatthe invention be limited to the exact details shown and described exceptas necessitated by the appended claims.

=I claim as my invention:

l. A dynamometer which comprises, a casing for cooling liquid, means forpassing a cooling liquid into and ythrough said casing, a hollow drumcarried in said casing and in contact with the cooling liquid in saidcasing,

Yrneans for rotating said drum in said casing from a prime -mover undertest exteriorly of said casing, braking Ymeans Within said drum forfrictionally contacting the inner wall of said drum, a torque-shaftextending through said casing and drum for carrying said braking meansin said drum to transmititorque occasioned by engagement of .-saidbraking means and drum, and torque-measuring .eans connected to Vsaidtorque-shaft exteriorly of said casing for measuring the torque of saidtorque-shaft.

2. A dynamometer which comprises, a closed casing for coolingliquid,.means for passing a cooling liquid into and through said casing,a hollow drum carried in said casing and in contact with the coolingliquid in said casing, lmeans for rotating said drum in said casing froma prime for converting torque to liquid pressure, and means coneasesnected to said torque-converting means for measuring said liquidpressure in said torquerconverting means.

3. A dynamometer which comprises, a casing for cooling liquid, means forcirculating a cooling liquid through said casing, a closed ho'rlow drumcarried in said casing and in contact with the cooling liquid in saidcasing, means for rotating said drum in said casing from a prime moverunder test ex.eriorly of said casing, braking means Within said drum forfrictionally contacting the inner wall of said drum, said braking meansincluding hydraulic means for urging said braking means into frictionalcontact with said inner wall of the drum, a torque-shaft extendingthrough said casing and drum for carrying said braking means in saiddrum to transmit torque occasioned by actuation of said hydraulic means,means exteriorly of said casing connected to said hydraulic means forcontrolling the actuation of said hydraulic means, and torque-measuringmeans connected to said torque-shaft exteriorly of said casing formeasuring the torque of said torque-shaft.

4. A dynamometer which comprises, a casing for cooling liquid, means forcirculating a cooling liquid throughV said casing, a closed hollow drumcarried in said casing with its exterior in contact with the coolingliquid in said casing, a shaft extending through a VWall of said casingand connected to said drum for rotating said drum in said casing from aprime mover under test exteriorly of said casing, braking means withinsaid drum for frictionally contacting the inner wall of said drum, atorqueshaft extending through said casing and drum carrying said brakingmeans in said drum to transmit torque occasioned by engagement of saidbraking means and drum, torque-converting means connected to saidtorqueshaft exteriorly of said casing for converting torque to liquidpressure, and means connected to said torqueconverting means formeasuring said liquid pressure in said torque-converting means.

5. A dynamometer which comprises, a casing for cooling liquid, means forpassing a cooling liquid into and through said casing, a hollow drumcarried in said casing and in contact with the cooling liquid in saidcasing, means for rotating said drum in said casing from a prime moverunder test exteriorly of said casing, braking means Within said drum forfrictionally contacting the inner Wall of said drum, a torque shaftextending through said casing and drum for carrying said braking meansin said drum to transmit torque occasioned by engagement oi said brakingmeans and drum, said braking means comprising'a holder carried by saidtorque-shaft within said casing, said holder carrying a plurality or"angularlyV spaced cylinders, a piston in each cylinder, frictionengaging means carried by each Vpiston for rictional engagement with theinner Wall of the drum when saidV pistons are moved, and means exteriorof said casing and drum for actuating said pistons to engage saidfriction engaging means and with said drum to anni tor ue to saidtorque-sha t, and torque-measuring means connected to said torque-shaftexteriorly of said casing for measuring the torque of said torque-shaft.

6. A dynamometer which comprises, a casing for'cooling liquid havingopposite end walls, means for circuiat-v a. prime mover under testexterior of said casing, a torque-YY sha'ft extending through theopposite end wall of the cas'- ing and through said drum, saidtorque-shaft being relatively rotatable with respect to said drum, aholder car-` ried by said torque-shaft Within said drum, oppositelydisposed radially extending cylinders carried by said holder, a pistonin each cylinder, a shoe carried by the Vhead of each piston, a segmentof friction material disposed radially outwardly from each shoe anddisposed Y adjacent the inner wall of the drum, said torque-shaft beingprovided with a bore connecting the radial inner end of each cylinderwith the exterior of said casing, means connected to the outer end ofsaid bore for passing liquid under pressure through said bore and intosai-fl cylinders to frictionally engage said friction material and theinner Wall of Said drum and transmit torque from said drum to saidtorque-shaft, and means connected to said torque-shaft exteriorly ofsaid casing for measuring the torque thereof. Y

7. A device as claimed in claim 6 wherein driving means is carried bysaid Erst-mentioned shaft, and a tachometer is remotely connected tosaid driving means for measuring the rate of rotation of said rstmentioned shaft.

8. A device as claimed in claim 7 wherein said means for passing liquidunder pressure to said cylinders is remote from said casing.

9. A device as claimed in claim 8 wherein said torquemeasuring means isremote from said casing.

l0. A dynamometer which comprises, a casing for cooling liquid havingopposite end walls, means for circulating a cooling liquid through saidcasing, a closed hollow drum rotatably carried in said casing with itsexterior surface in contact With the cooling liquid in said casing, adrum-driving shaft extending through one of said casing end walls andconnected to said drum for rotating said drum from a prime mover undertest exterior of said casing, a torque-Shaft extending through theopposite end wall of the casing about which said drum is rotatablydisposed, said torque-shaft being in axial alignment with saiddrum-driving shaft, a holder carried by said torque-shaft within saiddrum, friction engaging means carried by said torque-shaft within saiddrum, means disposed exteriorly of said casing for actuating saidfriction engaging means to frictionally engage said torque-shaft anddrum and apply torque to said torqueshaft, and means connected to saidtorque-shaft for measuring the torque thereof.

References Cited in the iile of this patent UNITED STATES PATENTS2,028,374 Anderson Ian. 2l, 1936 2,048,053 Bennington July 21, 19362,162,757 Shaw June 20, 1939 2,191,261 Roberts Feb. 20, 1940 2,392,702Saunders Ian. 8, 1946 2,719,620 McDonald Oct. 4, 1955 2,928,509 Del SoleMar. 15, 1960 FOREIGN PATENTS 583,956 Great Britain Ian. 3, 1947

